Method of preparing blanks for producing containers such as metallic cartridge casesor the like



March 7, 1944. w CLARK 2,343,253

METHODOF PREPARING BLANKS FOR PRODUCING CONTAINERS SUCH AS METALLICCARTRIDGE GASES OR THE LIKE Filed Feb. 12, 1941 "NEW A541 24 Jill-"NIHI5 Ill -INVENTOR WALTER R. CZfIRK ATTO RN EYS Patented Mar. 7, 1944METHOD OF PREPARING BLANKS FOR PRO- DUCING CONTAINERS SUCH AS METALLICCARTRIDGE CASES OR THE LIKE Walter 'R. Clark, Bridgeport, Conn.,assignor to Bridgeport Brass Company, Bridgeport, Conn., a corporationof Connecticut Application February 12, 1941, Serial No. 378,592

(Cl. 29-148) I 6 Claims.

This invention relates to metallic articles and to methods of preparingthe same. More particularly it relates to ordnance articles and to themethods of manufacturing the same.

In the preparation of cups for use in making cartridge casings, it hasbeen customary to stamp circular blanks from sheets of metal and thenform the cartridge cups from these circular blanks. Such practice ofstamping circular blanks has been very wasteful inasmuch as 40% to 50%of the primary sheet from which the blanks are stamped remains as scrapor waste metal which must be reprocessed into sheet form for furtheruse. There is at the present time an alarming shortage of productivecapacity necessary to reprocess the scrap primary metal and suchreprocessing must be avoided as much as possible. I

It is a principal object of this invention, therefore, to provide novelmethods of providing blanks from primary sheets which reduces the wasteor scrap to as low as 5% to 6% of the said primary sheet.

The savings entailed by the practice of the methods embodied in thisinvention are enormous. For example, it has been found that in theproduction of 100,000 twenty mm. cartridge cases, practice of theprocesses of this invention saves reprocessing of some 20,000 lbs. ofmetal per day. In any expansion, say to three times the capacity justmentioned, the savings in avoiding reprocessing of some 60,000 lbs. or30 tons of metal daily are enormous.

It has been found that where, for example, the ratio of thickness ofblank to diameteris not greater than 1 to 20, that polygonally shapedblanks, preferably hexagonal or octagonal, can be worked into blankshaving circular cylindrical form or other form with continuously curvededges without destroying the utility of the blanks for use inmanufacturing cartridge cups or the like.

The ability to use polygonally shaped blanks permits the severance of amaximum number of metal blanks from a primary sheet and reduces scrap toas low as 5% or 6% of the total sheet.

To efiect this great economy, the sheets are divided and separated intostrips along zigzag lines corresponding to the outlines of a pluralityof contiguous polygons arranged in echelon. The so separated strips areeach then further divided into separate polygonally shaped blanks. Eachof these blanks is then subject to treatment in suitable dies or thelike which act on the blank in such manner as to force metal from thebody of the blank to form segmental portions between the apices of theoriginal polygons so that the resultant blanks have a continuously.regularly curved perimeter free of sharp points or facets. Such blanksare then treated in usual dieing operations to form cartridge cups orthe like. Since the perimeters of the blanks are continuously andregularly curved as a result of the treatment described, they presentsmooth unbroken edges when upturned in the cu -forming, dieingoperations and require no trimming of any kind.

It is another object of this invention to provide methods of treatingpolygonally shaped blanks preliminary to cup forming operations so as toform blanks having continuously regularly curved edges whereby thenecessity of trimming to provide uniform cup edges is eliminated.

It is another object of this invention to provide methods of formingpolygonally shaped blanks into blanks having regularly continuouslycurved edges without trimming and by utilization of metal from theindividual bodies of the blanks to effect the said curved edges. Suchutilization of metal has been found not to destroy the utility of the sotreated blanks for cup formation.

To the accomplishment of the foregoing and such other objects as mayhereinafter appear, this invention consists in the novel product andmethods hereinafter described and then sought to be defined in theappended claims, reference being had to the accompanying drawing whichshows, merely for the purposes oi illustrative disclosure, preferredembodiments of the practices of the invention, it being expresslyunderstood that variations may be made in practice without digressingfrom the inventive idea.

In the drawing, in which similar reference characters denotecorresponding parts:

Fig. 1 is a fragmentary plan view of a main sheet of material such asmetal, on which has been superposed the pattern of stampings into whichthe main sheet is to be divided and the figure also illustrates theseverance of strip from the main sheet:

Fig. 2 illustrates a further step in the process of preparing theblanks, and particularly the severance of polygonal blanks from the saidmain strip;

Fig. 3 illustrates a modified means of laying out a primary sheet forseverance into polygonal blanks;

Fig. 4 illustrates the manner of severance of the polygonal blanks fromthe primary sheet or strip of Fig. 3;

Fig. 5 illustrates one type of means for shaping the individualpolygonal blanks into blanks having regularly, continuously curvededges, and illustrates in particular a vertical section of a die for soshaping said blanks;

Fig. 6 is a plan view taken along line 5-6 of Fig. 5 and viewed in thedirection of the arrows;

Figs. 7, 8 and 9 illustrate various cross sectional shapes which theblank treated in the die of Fig. 5 may have;

Fig. 10 illustrates a second type of means for shaping the individualpolygonal blanks into blanks having regularly, continuously-curvededges, and illustrates in particular a vertical section of a second formof die;

Fig. 11 is a plan view taken along line llli of Fig. 10 and viewed inthe direction of the arrows;

Fig. 12 illustrates in sectional elevation a cup forming die in whichthe blanks of Fig. 7, 8 or 9 may be treated to form a cartridge cup orthe like; and

Fig. 13 illustrates in vertical section, a cartridge cup formed by thedie illustrated in Fig. 12.

Referring now to the drawing, lll denotes a main sheet of metal, such asbrass or any other suitable metal or alloy.

This sheet I is first severed in suitable apparatus (not shown) alongthe zigzag lines ll, l2 into strips l3. The zigzag lines may beconveniently described as consisting of lines defining pairs of adjacentedges II, I! of each of a plurality of polygons l arranged in echelonand contiguous to each other along another edge iii of each of saidpolygons, or more broadly as lines defining outer edges of a pluralityof polygons arranged in echelon and contiguous to each other. The widerthe sheet the more polygons may be arranged in echelon. The scrap metalpieces l4 represent a very low percentage of the total sheet l0,amounting to as low as 5.5% of the total sheet. This percentage varieswith the width of the original sheet.

The said strips l3 are each then divided into the individual polygonallyshaped blanks l5 by severance from the strip along the continuous linesor edges l6. It will be noted from Fig. 1 that the blanks l5 havehexagonal shape. will be noted further that the division of the stripsl3 from the sheet is such that when the strip is separated into hexagonsl5 one apex only lla, l'lb respectively of the two outermost hexagons l5lie at the opposite marginal edges A, B of the strip while the edges orsides of the said hexagons adjoining the respective apices are at anangle with the said marginal edges. These blanks l5 could be useddirectly for the manufacture of cartridge cups but if so used, the upperedge of the formed cartridge cup would be irregular and would requireadditional trimming or machining to remove the scallops with necessarywaste of the metal trimmed on.

An alternative method of providing such blanks is to sever individualblanks l5, from strips lfla (Fig. 3) along the lines lfia and lib in themanner indicated in Fig. 4 The percentage of scrap metal pieces Ha ishigher than that of pieces I of Figs. 1 and 2 though considerably lowerthan if circular blanks are directly out. In the latter case the scrapskeleton may run as high as 40% of the original sheet. Blanks l5 areshown as octagons.

To eliminate the necessity for trimming or machining, the blanks I! orI! obtained in one of the ways described are now treated in one ofseveral ways to round the edges and in the embodiment shown producecylindrical disks l5'a without trimming and by working the body of themetal in such manner as to provide illl therefrom forming segments whichfill out the facets of the polygonal shape changing it to a continuouslyregularly curved or cylindrical disk having circular or other desiredform.

One manner of effecting this result is to place each blank l5 or II in adie I! having a circular wall l9 and a diameter substantially equal tothat between opposite pairs of apices l! or II of the polygonal blank.The die has a flat convex or concave bottom 2. and a bore thereinthrough which an ejector plunger 2| may be suitably operated. A presserplunger 22 movable into and out of the die I! through its open top isprovided. This plunger may have either a flat pressure surface 23 or thesaid surface may be convex or concave depending on the shape of thebottom 2|, corresponding shapes preferably being used.

With a blank IE or I! in place in the die It, sufficient pressure isapplied to the pressure plunger 22 so that its engaging surface actingon the surface of the blank l5, forces metal from the body of the blankto fill substantially all the segmental clearances 24 between theoriginal facet edges of the polygonal blank and the wall IQ of the die.Upon removal of the blank Ila from the die, it has a regular curvedperimeter corresponding to that of the wall l9 and, while thinner inregions of its body, is suitable for immediate use in forming acartridge cup. Since its edge is now regularly curved, the cartridge cupwhich can be formed therefrom has a regular smooth top edge which doesnot require trimming.

Another manner of treating the polygonally shaped blanks is to provide ahollow die 28. This die has an entering zone ifshaped to polygonal formmatching that of the blank IE or li'i The zone 29 gradually merges intoa curved or cylindrical zone 30 corresponding in shape to the ultimateshape of the desired finished blanks.

This zone 30, in the embodiment shown, has circular cross section. Theblanks l5 or l5 are piled at the entry to zone 29 and forced through thetwo zones of the die emerging from the zone 30 as blanks lib having therequired cylindrical shape. During passage through the die, flow ofmetal from the apices l! of the disks l5 to form the circular edge iseflfected. To prevent thickening of the regions of the edges sufflcientfriction is provided in the die and long cylindrical portion thereof andcounter pressure may be exerted on the pile from the emerging end of thedie II. The cylindrical disks or blanks lib formed in this way are nowready for use in preparing cartridge cups.

Other methods of treating the polygonal blanks to reduce them tocylindrical shape iia may be employed. For example, they may be piledand forced through a. set of swaging dies with enough force applied toeither end of the pile to force the metal to flow circumferentially inthe blank rather than to thicken up the same.

The blanks lia, li'a or l5"a or lib formed While this invention has beendescribed spe- I cifically with reference to the preparation ofcartridge cups, it is to be understood that the method of first severingpolygonal blanks from sheets in the manner described and then subjectingsaid blanks to operations transforming them into blanks havingcontinuously uniformly curved edges by causing flow of metal from thebody of the polygonal blanks may be utilized wherever it is desired toprepare seamless metallic casings having edges which are uniform andwhich do not require trimming. There is no intention, therefore, oflimitation either to the exact details of process described or to thesingle application described. Other modifications and uses within thescope of the appended claims are contemplated. For example, while theblanks l5 and I5 are shown respectively as hexagons and octagons, otherpolygonal forms of blanks are contemplated as within the scope of thisinvention.

I claim:

1. That improvement in the preparation of metallic blanks for theproduction of casings comprising providing sheets of metal, dividingsaid sheets into strips along zigzag lines defining outer edges of aplurality of hexagons arranged adjacent each other in echelon,separating individually hexagonally shaped blanks from said strips, sothat in each strip one apex only of each of the two outermost blanksseparated therefrom lies in its respective marginal edgeof said strip,while the edges of said blanks adjacent respective of said apices are atan angle with the respective marginal edges of said strip, and operatingon each of said hexagonal blanks individually to cause metal from theblank to fill out the straight edges of the hexagon and transform thesaid blank into one having a substantially circular perimeter.

2. That improvement in the preparation of metallic blanks for theproduction of casings, comprising providing sheets of metal andseparating said sheets into biased strips along lines defining outeropposite edges of a plurality of hexagons arranged adjacent each otherin echelon and separating individual hexagonal blanks from said strips,so that in each strip one apex only of each of the two outermost blanksseparated therefrom lies in its respective marginal edge of said strip,while the edges of said blanks adjacent respective of said apices are atan' angle with the respective marginal edges of said strip.

3. That improvement in the preparation of metallic blanks for theproduction of casings comprising providing sheets of metal, separatingsaid sheets into strips along zigzag lines defining pairs of adjacentedges of each of a plurality of hexagons arranged in echelon, contiguous to each other along another of the edges of each of said hexagonsand with one apex only of each of the two outermost hexagons lying inthe respective opposite margins of said sheet and with the edges of saidoutermost hexagons adiacent respective of said apices each at an anglewith the respective margins, separating each of said strips intoindividual hexagonally shaped blanks along the contiguous edges so thatminimum waste of material is effected, and shaping each of said blanksto cause metal of each blank to fill out the straight edges of itspolygonal shape and transform said blank into one having a continuouslycurved perimeter.

4. 'That improvement in the preparation of metallic blanks for theproduction of casings comprising providing thin, polygonally shapeddiscs of metal and moving said discs under pres sure in one directioncompletely through a die having a polygonal zone therein correspondingin shape to said discs, to and completely through a zone of said diehaving a continuously curved wall, whereby flow of metal from the apicesof each of said discsto the polygonal sides thereof is effected and saiddiscs emerge from said die with an entire, continuously curvedperipheral shape corresponding to that of said continuously curved wall.

5. That improvement in the preparation of metallic blanks for theproduction of casings comprising providing thin, hexagonally shapeddiscs of metal and moving said discs under pres-' sure in one directioncompletely through a die having an hexagonal zone therein correspondingin size to that of said discs, to and completely through a zone ofsaiddie having a circular 40 wall of smaller diameter than that of saidfirstnamed zone whereby fiow of metal from the apices of each hexagonaldisc to the hexagonal sides thereof is affected and said discs emergefrom said die with an entirely circular peripheral surface correspondingto that of said circular wall.

6. That improvement in the preparation of metallic blanks for theproduction ofcasings comprising providing a sheet of metal havingparallel opposite marginal edges, separating said sheet into stripsbiased with respect to said edges along zig-zag lines defining outeropposite edges of a plurality of hexagons arranged adjacent to eachother in echelon, and separating individual hexagonal blanks from eachsaid strip along contiguous edges of the said hexagons, the bias of saidstrips and their lengths being such that one apex only of each of thetwo outermost hexagonal blanks severed therefrom lies in the respectivemarginal edge of each said strip while the edges adjacent to each ofsaid apices are at an angle with the respective marginal edges.

CERTIFICATE OF CORRECTION. Patent No. 2,515,255. March '7, 191m.

' 'wamsn a. cum.

It is hereby certified that error appears in the printed specificationof the above nunbered patent requiring correction as follows: Page 2,first column, line 14.7, for 'continuous" read --contiguous-; page 5,first colline 36, claim 1, for individually" read --individua1--;andthat the said Letters Patent should be read with this correction thereinthat the same may confonn to the record of the case in the PatentOffice.

Signed and sealed this 25th day of April, A. D. 191 1;.

Leslie Frazer (Seal) Actingcommissioner of Patents.

